This invention relates to electrical wiring box structures. More particularly, it is connected with a formed metallic electrical wiring device having integral wiring device mounting means.
Numerous methods have been disclosed in the prior art for attaching the mounting screw of an electrical wiring device to the wall structure of an electrical wiring box. In the caseof wiring boxes formed of plastic or other moldable materials, mounting methods have been disclosed which depend either upon a threaded screw opening in the box wall structure or a screw engaging metal insert which mates with the box wall. The former arrangement is not desirable because of the ease with which the threads formed in the plastic box wall become stripped. In the latter arrangement, the provision of a metallic insert adds to the overall cost of the box and the installation time. Many of these schemes provide, however, for the easy push-insertion of the wiring device mounting screw during installation.
In the case of wiring boxes fabricated of metal, it has been the common practice in the trade to simply form threads in the wall structure of the wiring box. In such metal wiring boxes, typically no provision is made for the rapid push-insertion of the wiring device mounting screw, and the mounting screw must be inserted by the time consuming action of turning the full length of the screw into the threaded opening.
In any event, it would not be obvious to modify the box in some manner to provide for push-insertion of the wiring device mounting screw since push-insertion mounting normally requires high resiliency in the mounting device to have the mounting screw threads engaged. Metal wiring boxes are normally made from commercial quality, low-carbon, cold-rolled steel and thus do not have a high degree of resiliency.